Screw-propeller



E. A. VESSEY.

SCREW PROPELLER.

APPLICATION FILED Nov.29, 1918.

1,365,132. Patented Jan. 11, 1921.

5 SHEETS-SHEET INVENTOR ECAV'esseLy,

E. A.. vEssEY. scnfw PRoPELLER.

APPLICATION FILED NOV. 29. 1918.

1,365,132, Patnted Jan. 11, 1921.

5 SHEETS-SHEET 2.

//l/lla INVE NTOR I'-A-Vesse`y,

` BY %M MmRNEY E. A. VESSEY.

SCREW PROPELLER.

APPLlcATloN man Nov. 29. 1918. .Patented Jan. 11, 1921.

5 SHEETS-SHEET 3.

INVENTR Ef?. Vessey.

` ATTORNEY E. A. VESSEY.

SCREW PROPELLER. APPLICATION FILED nov. 29. I9Is.

1,865,132'. Patented 1111.111921.

5 sIIEETs-SIIEET 4.

INVENTIIR A V'essay. ATTORNEY E. A` VESSEY.

SCREW PROPELLER.

APPLICATION FILED Nov.29. |918.

Patented Jan. 11, 1921.

NEI'

n /MMQATTOR AUNITED STATES ERNEST .AIBINGTON VESSEY, FARNBOMGH, ENGLAND. y

soanw ritoriimnit Specicatlon of Letters Patent.

Patented Jan. 11, 1921.

Appiicatio'n'nie'd November' 29,. i918. serial No. 264,761.

To all 4whom it may concern.'

Beit known that I, ERNEST ABiNo'roN VassEY, a subject of the King of Great Britain and Ireland, and residin at St. Newitt Ashley Road, Farnborough, in the county of Hants, England, have invented certain new and useful Improvements Relating to Screw-Propellers', of which the following is a specification.

This invention relates to screw propellers of the known type in which the eif.ective diameter may be varied, and a variation of diameter is caused, if desired, to effect a variation of pitch ofthe propeller blades. The invention is applicable to propellers working in. liquids as well as in fire screwsl or other elastic fluid propellers.

,The principal objects of the present invention are to simplify the construction of such propellers, to avoid the difliculties usually arising from the large 'centrifugal forces which come into operation, to provide for the secure holding of the separate blades at their root ends, and generally to enable improved results to be attained by the efficient control of the required blade` movements.

The invention comprises one or more of the following features, viz:

(a.) Arranging that the centrifugal force acting on the blades is resisted by simple tension elements connected so as to practically balance one another;

(b) Arranging theblade ends in approximately radial sockets in the hub, permitting approximately radial movement under centrifugal force, and utilizing this movement l under control of the tension members to obtain an increased effective propeller diameter (d) Employing wedge elements under the action of centrifugal force to secure the blade ends; and

(e) Arranging the hub sockets at a slight angle to the plane perpendicular to the shaft axis and/or to the radial planes through the Utilizing the radial movement in the shaft axis, so as to provide a component of centrifugal force whereby centrifugal force more or less relieves the blades of l bending stresses due to the air reactions.

The invention further consists .in jointing the inner en ds of the connective tension .elements to a ring element slidable axially relative to the hub, by the axial movement of which the effective diameter and effective pitch of the propeller can be varied within predetermined limits.

The invention also consists in the combination with the said devices of positively operated means for controlling the effective pitch of the propeller. ,v I append drawings illlustrating my invention.

Figure 1 is a view projected on a plane parallel to the shaft axis, the upper part being in section.

- Fig. 2 is a similar view showing another formA ofl control mechanism.

Fig. .3 is a View of a modified formof part of the mechanism which may be applied to a hollow propeller shaft.

Fig. et is the plan view of the front portion of a tractor aeroplane showing one form of the hand-operated -control mechanism by means of which the variation in pitch is effected.

Fig. 5 is a sectional view giving a vmodified detail of the divided nut and thrust bearing, forming part of the mechanism shown in Fig. 4.

Fig. 6 is a view at right angles to that shown in Fig. l, the upper part having an outside detachable cover removed.

Figs. 7 to 9 relate to the form of the control mechanism as shown in Fig. 1.

In carrying the invention into effect in A one form, by way of example, as applied to a four-bladed air propeller, I construct a light metal shell or hub H having tubular sockets 2, one for each of the ,blades B.

These sockets may be separable, or may be welded on vto the hub shell, or be solid therewith.- These tubular sockets carry at their radially inner ends cylindrical parts Bof less'fdiameter internally threaded, one side of the thread being formed solid, and the other side in a bushing 4, so held that the to be free to expand or contract in diameter'.

thread can be `maintained in close contact on the male thread 6, and back lash thus prevented. vThe male thread 6 is formedon the,`

outside of a lcylindricaly projection or boss 7 'i on the radially inner end of a cylindrical shell 8 fittin within the aforesaidradially -inner end o the socket 2.' This shell"m 84 forms a protective casing in fixed relation-I shi to the woodenspigot end 9 of the` propel erfblade, which spigot is preferably turned with a double conical surface, a short or steep conical part 10 bein formed attm; root of the shaped Ypart o of this conical part the second opposed coni' cal surfacev14ris formed by reducing the diameter of .this "portion" of the spigot-9 Eto.-

ward'its end 15, whichabuts against the bottom of the shell 8; A'conicalspace is thus left*betwecn thev long cone of .the

spigot and the 'cylindrical surface-ofthe` shell into 'whichfits largest/diameter fits. This conical space I lill with an expansible wedge sleeve 16, which is slit at anumber of .y

places '17 alternately from'veachedge, sok as This wedge sleeve is placed within theshell 8, and the conical surface lll'of the spigotisI placedwithin it. Ascrewed conical `rin 18 made in halves for convenience of assem ly,

. fitting the neck of the blade, is then screwed within the shell 8, andthe spigot of the` lace.4 vA transk blade is thus clamped in versepin'2() may be applled throughthe shell 8, wedge sleeve 16, and spigot-9 of the s blade,passing through two'of the beforementioned slits inthe wedgesleeve, so that verse pin 20 isthen made preferably long enough tofpr'oject permanently through'the holes in the' tubular socket, thuspreventing the blade from iiyin yoff in case'of accident to'themechanismf lhen the blades become subjected to centrifugal forcethewedge securelyI beds against the'long cone of the spigot oftheblade, locking the blade firmly andtaking up any slack which may occur,

e. g. from shrinkage. 'Inthe example illustrated,y the transverse piny 20f`is notmade long enough to projectthrough'the hub, and the wedge sleeve 16 is so short vthat the-transverse 'p in doeslnot pass throughl it.

`As an valternative `method for obtaining angular motion of the blade as a result of radial movement, it may-be convenient instead of providing the screwed extension of n the propelle blade, and' from thefmaximum diameter`12 .y

the hub socket and shell for the blade end to adapt the transverse pin to work in spiral slots ormed in the walls of the tubular socket, 'il-means j for` adjustingf' for back lash and wear being provided.'y Such alternative method isnot illustrated in the drawings.

The tubular sockets are preferably set at a slight. angle to the plane at right angles bending stress' Vdue to"v the axial thrust.

Further, the tubulargsockets Aand the faxes,

'n to ,thev propeller shaft, so that an axial com- Aponent ofthe centrifugal force is applied 'to the "blade in opposition to the thrust,.andy lthusthe bladelvisniore or less relieved of of the bladesl mayfbe arranged at `a"`sliglit i' angle tothe radial planes through the' shaft axis, thusin asimilar manner. relieving the blades-fofy bending stress due tol'torquef The externally screwedl boss 7 on'the shell" 8 rsheathingthe bladeend is socketed toireceive thespherical end 22'of' a short con-' lnecting rod 23, which is adaptedto; project' through an opening in the inner endvfof the boss.y This i connecting rod endris lheld in place byy airing 24; screwed' intoj ,the outer nectingfrod is forked at,25,'an'd embraces a` lug 26 projec ting*froni a `ring ,element2,714

end offtheboss. vThe lother end 'of the conmovableaxially onfthe exterior ofthe central sleeve 28 of the hub shell. 'fTh'e forked fend of the connecting rod isjointedto the lug allanchored to the same ring element; vThe principall componentv of the centrifugal force* on each,vr blade is thus balanced` through' the element.` Thesliding ring ^element`27 within;

the hub, which 'is linked'to' the-l`4 blades,` is:

l 26 by..meansrof the pin I30. '`Eachoftheu blades is similarly mounted, sotbatthey are conveniently also provided withfal` springl vmore or less balancing the axial com onent's" of the forces applied by centrifugal orceto" the blades. Alternatively kthere may `be a series of springs arranged around the ,"ring element and parallel to thefaxis, the resultant effort of the said series lof springs being co-axial with the shaft.'l The ring element 27" is provided also with aunurnber of studs 31, which project through the hubcasing,`and

are screwed into a flanged ring 32'e`xtern'alto l 7 the hub slidable i axially'on the propeller shaft and which is provided with ball thrusts, so thatV axial forces ineeither 'direcL tion can be applied to it by means of a nonrotating' ring 3.3' between the ball thrust "i bearings.. The said thrust bearings `are/independent ofthe propeller-shaft thrustbear-v ing, which is not shownV on` "the drawing. Pins 34Ck on the ringy 33,*.are linked up. by means of the suitable lever It with a `screwed rod, under the control ofa` divided carried inv suitable bearings, andoperated by means of a hand wheel g under the control of the pilot, (Fig. 4).

`Should the propeller shaft beihollowffor example, when itis geared to the engine shaft, the screwed rod will, in this case, pass directly through the center of the hollow shaft to engage a smaller ball thrust fitted in an extension of the ring element 27. One form of this arrangement is shown in Fig. 3. The ring` element 27 is provided with a cylindrical extension a screwed externally to receive the thrust sleeve b which is adapted at the outer end to accommodate-the ball thrust c.' The'ball thrust c is connected by means of the flanged sleeve cl to a socket e' which is in turn attached rigidly to the operating rod f which passes through the center of the hollow shaft g of the engine,

and is screwed at the other end. The screwed rod is thereforecapable of exerting pressure in either direction to the rapidly revolving to take the pressure of the springwhen the screw propeller is at rest.

One method for operating the mechanism, which is particularly applicable to the design shown in Fig. 2, 1s shown in Fig. 4. The lever h which extends horizontally across the front of the aeroplane frameis pivoted at one end and forked at the other j to engage the divided nut 7:. At or near the center of its length the lever is enlarged to surround the stationary ring 33 of.the propeller to which it is Zpivotally connected y means of the bushes which are capable of slight sliding motion in the lever. These bushes are bored to receive the pins 34 of the stationary ring' 33., `Penetrating the divided nut la -is the screwed rod fm! which passes through the thrust bearing n and a second bearing 0 conveniently fixed to the instrument board p of the aeroplane. A handwheel g is fitted to the screwed rod, thus enabling it to be easily manipulated from the pilots seat.

The end of the screwed rod m where it passes through the divided nut and thrust bearing is shown in enlarged modified section in Fig. 5. The main part of the nut lo is provided with pivots s which engage the -fork end of the lever by means of bushes t.

One end of the nut 7c is enlarged land screwed internally to receive a gland ring u. The gland ring is screwed internally to receive the screwed rod and externally to fit the internal screw in the enlarged part of the nut. The external threads may be of opposite hand or different pitch to the internal threads thus providingr a differential adjustment. clip o. The thrust of the screwed rod is taken on the collar w which abuts in one direction against. thebearing n and at the other against the internally flanged nut y.

The alternative form of the control mechanism shown in Figs. -7 to 9 (which is The gland ring is locked by the i the preferred form) comprises more convement means for providing the required axial movement of the ring element 27 and \key pin 64 which engages in a slot formed in the rim of the sleeve. Integral with or screwed to the sleeve is an annular surface cam 65, which engages with asimilar cam formed on the end of a second co-axial sleeve 66. On the external surface of the second sleeve 67, but not necessarily surrounding it, are cut skew teeth which engage with a worm 68 running in bearings 69 and 70 in the case. One bearing 69 is, for convenience of assembly, made detachable. A ball thrust bearing 71` is provided toy take the end thrust of the worm. The second sleeve is adapted to be displaced circumferentially in a bearing 72 in the case, but is prevented from moving axially by means of a screwed collar 73 which is locked by a grub screw 7 4. The second sleeve is bored to receive a thrust bearing 75 which abuts in one direction against a collar formed in the second sleeve and in the other against a shoulder formed on the adapter 76, if such is provided, or against a collar screwed to the external boss of the main hub. The case is provided with feet 77 by'which it is of tube fitting over and pinned. to the spindle of the worm is provided withan outer bearing 81 supported on the yoke and is fitted with a pulley 82 which, in the form shown, is coupled by means of a flexible cable to a control pulley 83 arranged to run on a spindle in a bracket 84: mounted conveniently to the pilots hand. .A handwheel 85 is fixed to the spindle of the control pulley, whereby the pilot may rotate the pulleys and thereby the worm, in either direction.

The action of the mechanism is as follows:

If the worm is` rotated by the pilot in either direction by means of the handwheel pulley, cable and second pulley spindle, the second cam is rotated and, since it cannot move axially, the latter will either push the first 'cam axially to the left against the axial force from the flanged ring, or allow it to Sure.

move to the right .under the action of that may be varied within the limits of the apparatus.

When the propeller is brought to rest, either voluntarily or through engine failure, the flanged ring will move to the left under the action of the main balancing spring until it comes to rest against the back face of the main hub. In this case, the two cams are separated, but without rotation, consequently when the propeller is again started and has reached a speed sufficient for the centrifugal force to overcome the balancing spring the cams engage once more in precisely the same relative positions as before the propeller was brought to rest. The propeller will therefore restart with the same pitch as it had before stopping, provided no movement of the pilots handwheel has taken place.

The resultant axial force upon the fianged ring within reasonable variations of pro* peller speed should be arranged to act toward the right. This is accomplished by so proportioning the balancing spring that the centrifugal component is under all run-- ning conditions in excess of the spring pres- The consequence of this is that any back lash which may exist in the operating mechanism now described has no effect upon the propeller pitch.

The hub shell is provided conveniently with a stiffening flange 52 at its open end, which is lightened, say, by drilling, thus providing conveniently for balancing of the structure. A light cover 53 to close the open end of the hub shell is also provided. I provide also for the casing-in of the hub periphery with a light shell 54 to reduce the windage of the sockets on the hub. I may also round off the contour at the end of the hub by a curved conical disk 55, in order to reduce air resistance. This disk is made detachable for easy access to the mechanism.

In cases where it is not desired to vary the pitch of the propeller, but only to alter its effective diameter at will, I may omit the coacting screw elements adapted to rotate the blades. It may be desirable again, in some cases, to get the combined effect of increased effective diameter along with pitch variation, and by the present invention, any desired combination of these can readily be obtained.

It is not essential that the radial and angular movement of the blades should be inter-dependent e. g. the radial movement may be accomplished by the. means de, scribed, but the screw elements for securing the angular movement of the blades may be.

replaced by any other suitable means.

varied. For example, the method hereinthe. design may be considerably before described of securing the bladesto.

the hub may be unnecessary. u

Having now described my invention what I claim as new and desire to secure by Letvters Patent i`s :-4

l. A screw propeller comprising aV hub with approximately radial sockets, propeller blades having their spigot ends slidable relative to the hub sockets, a ring element slidable axially relative to the hub, connective tension elements each jointed at one end to the ring element and at the other end to the spigot end of one of the blades, .and means for displacing and controlling the ring element axially relative' to the hub and of checking its movement under the resultant -axial component due to centrifugal force on the blades and thereby effecting a variation of effective diameter of the blades.

2. A screw propeller as set forth in claim- 1, comprising co-acting screw elements on the spigot endso f the blades and on the hub sockets respectively, whereby relative radial movement is accompanied by a variation of effective pitch of the blades.

3. In a screw propeller as set forth in claim 1, the comblnation therewith of protective metal shells in fixed relationship to the wooden spigot ends of the blades adapted to be slidable relative to the hub sockets as aforesaid.

4. Means for firmly fastening the spigot ends of the blades to the protective shells referred to in `claim 3, comprising a cylindrical inner surface for each of the said shells, a longconical surface of decreasing diameter toward the inner end of the blade spigot, a neck of reduced diameter and a short conical shoulder at the outer end of the blade spigot, a ring made in halves screwed to the mouth of the protective shell and fitting on the said short conical shoulder and an expansible wedge sleeve fitting between the inner conical end of the blade the ring element referred to in claim l and checkingmits movement under theresultant axial component due to centrifugal force on theblades, comprising a thrust element cofaxiarll'fwith the propeller shaft in fixed relationship to the ring element, a non-rotating axially displacement element,

a ball thrust bearing between the two said elerotating axially displaeeable element, cam ments, and means for axially displacing the surfaces on the two said elements, a ball said non-rotating element. thrust bearing between the angulaily dis- 7. Means as set forth in claim 6,0o1nprisplaceable element and a shoulder in fixed 5 ing also Connecting elements projecting relationship to the propeller shaft, and 15 through the hub casing between the ring means for displacing the angularly diselement and the thrust element. placeable element.

8. Means as set forth in claim 6 oompris- In testimony whereofv I have signed my ing also an element displacealole angularly name to this specification. l0 but not axially in Contact with the said non- ERNEST ABNGTON VESSEY. 

